The present invention relates to a polishing stack for polishing a plastic sheet produced in a wide extrusion die, wherein the stack is comprised of at least two polishing rolls supported in frames and equipped with adjusting devices for the roll thickness.
A plastic sheet produced by means of a wide extrusion die generally passes two or more polishing gaps. In this case, the term plastic sheet refers to the still plastified sheet leaving the die as well as to the subsequently formed plastic film. Plastic sheets or films polished with a device of the described type are applied in particular for thermoforming purposes, e.g. in the packing industry.
A polishing stack of this kind is disclosed in DE 37 02 945 A1, which, however, is not provided with a gap adjustment.
The task of the present invention is to present a polishing stack for thermoplastic films that is distinguished by a complete compensation of all roll bearing and frame clearances and an extremely precise adjustment of the gap thickness.
The paramount aim is to eliminate the bearing clearances, to adjust the thickness of the gaps between the rolls, and to generate a roll bending force at minimum machine costs.